Image blur is a common problem in photography. Some common causes of blur in a photograph are subject motion, camera motion (shake), and focusing errors. Blur is a particular problem for casual or amateur photographers who may not know how to diagnose the causes of blur or how to change their photographic technique to improve their results. As new consumer camera models are being produced with zoom lenses capable of very long focal lengths, blur due to camera shake is especially troublesome.
Various devices and techniques have been proposed to help address the problem of image blur due to camera shake. For example, Murakoshi (U.S. Pat. No. 4,448,510) uses an accelerometer to detect camera shake, and provides an indication to the user of the camera if the acceleration exceeds a threshold level.
Satoh (U.S. Pat. No. 6,101,332) also senses camera shake, and combines the shake information with other camera parameters to estimate how much image blur might result. A set of light emitting diodes communicates the estimate to the photographer.
Another approach has been to automate the camera operation, and let the camera choose settings that will minimize blur. For example, Bolle et al. (U.S. Pat. No. 6,301,440) applies a variety of image analysis techniques in an attempt to improve several aspects of photographs. Sato (U.S. Pat. No. 6,487,369) monitors the camera shake and attempts to take a photograph at a time when the shake magnitude is at a local minimum, if possible.
Each of these approaches has its drawbacks. The above techniques may require the addition of expensive electro-mechanical components to a camera, thereby increasing the camera cost. The techniques may address only one potential cause of image blur. The techniques give the camera user little guidance about how to improve her photographs, and in fact, additional automation that reduces the photographer's control of the camera may even add to the mystery of why a particular photograph is blurred.
A solution to the problem of image blur is needed that also addresses these difficulties.